WO2010150807A1

WO2010150807A1 - Wireless base station device, mobile terminal device, and transmission electric power control method

Info

Publication number: WO2010150807A1
Application number: PCT/JP2010/060623
Authority: WO
Inventors: 大祐西川; 祥久岸山
Original assignee: 株式会社エヌ・ティ・ティ・ドコモ
Priority date: 2009-06-23
Filing date: 2010-06-23
Publication date: 2010-12-29
Also published as: JP2011009866A; EP2448338A1; JP5101568B2; US20120127911A1; US8958355B2; EP2448338A4

Abstract

Provided are a wireless base station device, mobile terminal device, and transmission electric power control method capable of combining conventional techniques of reducing interference between cells with UL CoMP. A wireless base station device comprises a UL CoMP processing section (2085) that applies UL CoMP to a mobile terminal (100₁) when a difference (PL₂-PL₁) between a transmission loss (PL₁) between said mobile terminal (100₁) and a base station device (200₁) to which said mobile terminal (100₁) is connected and a transmission loss (PL₂) between said mobile terminal (100₁) and a base station device (200₂) having the smallest transmission loss with respect to said mobile terminal (100₁) is within a predetermined range, and a transmission electric power control section (2089) that controls transmission electric power when said UL CoMP is applied as well as controls transmission electric power when said UL CoMP is not applied.

Description

Radio base station apparatus, mobile terminal apparatus, and transmission power control method

The present invention relates to a radio base station apparatus, a mobile terminal apparatus, and a transmission power control method for controlling transmission power during uplink CoMP (Uplink Coordinated Multiple Point reception).

In the LTE (Long Term Evolution) system defined by ^{3GPP (3 rd Generation Partnership Project)} , in the uplink, a low peak-to-average power ratio: realized (PAPR Peak-to-Average Power Ratio), the increase in the coverage Effective SC-FDMA (Single-Carrier Frequency Division Multiple Access) is adopted. Therefore, basically, radio resources of a certain frequency and time are allocated to one mobile terminal apparatus (UE: User Equipment) by scheduling in the radio base station apparatus, so that users in the same cell are in the frequency and time domain. At right angles. However, since the LTE system is based on one-cell frequency repetition, interference from neighboring cells is large, and in particular, the interference level from UEs existing at the cell edge is high. For this reason, in order to compensate for such neighboring cell interference and maintain a constant reception quality, it is necessary to take measures against inter-cell interference.

As a countermeasure for inter-cell interference, the role of uplink transmission power control plays a large role, and the radio base station apparatus takes into account the propagation loss between the user and the radio base station apparatus and the interference given to neighboring cells. Therefore, it is required to control the transmission power of the mobile terminal apparatus so as to satisfy the received quality. In the LTE system, fractional transmission power control is adopted as a transmission power control method considering inter-cell interference.

The radio base station apparatus notifies the transmission power of signals (PUSCH (Physical Uplink Shared Channel), PUCCH (Physical Uplink Control Channel), SRS (Sounding Reference Signal)) transmitted in the uplink of the LTE system in a relatively long cycle. Open loop control based on parameters and propagation loss measured by the mobile terminal apparatus, and communication status between the radio base station apparatus and the mobile terminal apparatus (for example, received SINR (Signal to Interference plus Noise Ratio) in the radio base station apparatus) The transmission power of PUSCH is given by the following equation (1) (non-patent document 1). ).
_{P PUSCH (i) = min {} P MAX, 10log 10 (M PUSCH (i)) + P 0 _ PUSCH (j) + α · PL + Δ TF (i) + f (i)} Equation (1)
This fractional transmission power control can reduce inter-cell interference by setting the target reception power according to the propagation loss PL of the mobile terminal device (implemented with the parameter α of the open loop control).

FIG. 25 is a diagram for explaining fractional transmission power control. In FIG. 25, the vertical axis represents the target received power (P _{O —} _PUSCH ), and the horizontal axis represents the propagation loss (PL). Fractional transmission power control is set so as to reduce the target reception power of a mobile terminal device existing at the cell edge for the purpose of suppressing inter-cell interference. That is, if the propagation loss (PL) is large, the user is present at the cell edge, and if the propagation loss is small, it is considered that the user is present near the radio base station apparatus. The target received power of the user's mobile terminal apparatus is relatively increased, and the target received power of the user's mobile terminal apparatus at the cell edge is relatively decreased. The slope of the primary characteristic line of such a relationship is-(1-α).

Furthermore, as a countermeasure for inter-cell interference in the uplink, in the LTE system, both “UL Overload Indication (OI)” and “UL High Interference Indication (HII)” signaling (signaling via the X2 interface between radio base station devices). Is defined (Non-Patent Document 2). As shown in FIG. 26, the ULOI is used by a radio base station apparatus (neighboring cell) having a high reception interference level to notify the surrounding radio base station apparatus (own cell). For example, the radio base station of the own cell that has received ULOI performs control to reduce the transmission power at the cell edge. ULHII is used to notify resource base station apparatuses of neighboring cells in advance of resource block (RB) information to be allocated to the mobile terminal apparatus when the subordinate mobile terminal apparatus is located at the cell edge. The radio base station apparatus in the neighboring cell that has received ULHII performs control to perform frequency scheduling so as to avoid the RB.

On the other hand, in the LTE-A (LTE-Advanced) system, uplink multipoint reception (ULCoMP: Uplink Coordinated Multiple Point reception) is scheduled to be adopted as a further countermeasure against inter-cell interference (3GPP TR36.814). In this ULCoMP, as shown in FIG. 27, the radio base station apparatus of its own cell directly receives the desired signal transmitted from the mobile terminal apparatus and also transmits the desired signal transmitted from the mobile terminal apparatus to the radio of the neighboring cell. Receive via the base station device. That is, in ULCoMP, a signal that becomes a conventional interference wave is used as a desired signal, so that uplink reception quality can be improved, and in particular, it can be expected to improve the quality of mobile terminal devices at the cell edge. . In particular, in the LTE-A system, in addition to the conventional independent base station configuration, a remote base station (RRE: Remote Radio Equipment) that is a radio device at a transmission / reception point located away from the base station body is actively used. It is considered to enhance the effect of ULCoMP.

However, since this ULCoMP is a technology that uses a conventional interference wave as a desired signal, adopting the conventional inter-cell interference reduction technology (Fractional transmission power control, UL Overload Indication, UL High Interference Indication) in the LTE system, There is a risk of reducing the gain of ULCoMP. In addition, ULCoMP is not applied to all mobile terminal devices because of its large processing amount, and it is assumed that whether or not ULCoMP is applied is dynamically controlled according to the propagation environment of the mobile terminal device. The Although it is necessary to use a conventional inter-cell interference reduction technique and ULCoMP in combination, a method for realizing the technique has not been established.

The present invention has been made in view of such points, and an object thereof is to provide a radio base station apparatus, a mobile terminal apparatus, and a transmission power control method capable of using a conventional inter-cell interference reduction technique and ULCoMP together. To do.

The radio base station apparatus of the present invention includes a first propagation loss PL ₁ between a mobile terminal apparatus and a first radio base station apparatus to which the mobile terminal apparatus is connected, the mobile terminal apparatus, and the mobile terminal apparatus. On the other hand, when the difference (PL ₂ -PL ₁ ) between the second propagation loss PL ₂ and the second radio base station apparatus with the smallest propagation loss is within a predetermined range, the mobile terminal apparatus Multipoint reception processing means for applying uplink multipoint reception to the mobile station, performing transmission power control when applying uplink multipoint reception when applying the uplink multipoint reception, and performing uplink multipoint reception. Transmission power control means for performing transmission power control when the uplink multipoint reception is not applied when not applied.

The mobile terminal apparatus of the present invention includes an uplink multipoint reception notification signal processing means for receiving an uplink multipoint reception application / non-application notification signal transmitted from the radio base station apparatus, and transmitted from the radio base station apparatus. A transmission power control parameter receiving means for receiving the transmitted transmission power control parameter, and a transmission power control parameter different from the transmission power control parameter when the uplink multipoint reception is not applied when the uplink multipoint reception is applied. Transmission power setting means for setting transmission power by using.

According to the transmission power control method of the present invention, in the first radio base station apparatus to which the mobile terminal apparatus is connected, the first propagation loss PL ₁ between the mobile terminal apparatus, the mobile terminal apparatus, and the mobile terminal apparatus On the other hand, when the difference (PL ₂ -PL ₁ ) between the second propagation loss PL ₂ and the second radio base station apparatus with the smallest propagation loss is within a predetermined range, the mobile terminal apparatus Applying uplink multipoint reception to the mobile terminal apparatus and transmitting transmission power control parameters at the time of applying uplink multipoint reception to the mobile terminal apparatus when applying the uplink multipoint reception, Transmitting the transmission power control parameter when the uplink multipoint reception is not applied to the mobile terminal device when the point reception is not applied; and Receiving the transmission power control parameter transmitted from the first radio base station apparatus, and when applying the uplink multipoint reception, the transmission power control parameter when the uplink multipoint reception is not applied, And setting a transmission power using different transmission power control parameters.

According to the present invention, since transmission power control at the time of applying uplink multipoint reception is adopted when uplink multipoint reception is applied, conventional inter-cell interference reduction technology can be achieved without reducing the gain of uplink multipoint reception. And uplink multipoint reception can be used together.

It is a figure which shows the radio | wireless communications system which has a radio base station apparatus and mobile terminal apparatus which concern on embodiment of this invention. It is a figure for demonstrating the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 1 of the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 2 of the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 3 of the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 4 of the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 5 of the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 6 of the transmission power control method which concerns on embodiment of this invention. It is a figure for demonstrating the aspect 7 of the transmission power control method which concerns on embodiment of this invention. It is a block diagram which shows schematic structure of the mobile terminal device which concerns on embodiment of this invention. It is a block diagram which shows the structure of the baseband signal processing part in the mobile terminal apparatus shown in FIG. It is a block diagram which shows schematic structure of the radio base station apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the baseband signal processing part in the radio base station apparatus shown in FIG. It is a block diagram which shows the structure of the transmission power control part in the baseband signal processing part shown in FIG. It is a flowchart which shows the procedure regarding the notification of ULCoMP application / non-application of the transmission power control method which concerns on this invention. It is a flowchart which shows the other example of the procedure regarding the notification of ULCoMP application / non-application of the transmission power control method which concerns on this invention. It is a flowchart which shows an example of the procedure of the aspect 1 of the transmission power control method which concerns on this invention. It is a flowchart which shows the other example of the procedure of the aspect 1 of the transmission power control method which concerns on this invention. It is a flowchart which shows the procedure of the aspect 2 of the transmission power control method which concerns on this invention. It is a flowchart which shows the procedure of the aspect 3 of the transmission power control method which concerns on this invention. It is a flowchart which shows the procedure of the aspect 4 of the transmission power control method which concerns on this invention. It is a flowchart which shows the procedure of the aspect 5 of the transmission power control method which concerns on this invention. It is a flowchart which shows the procedure of the aspect 6 of the transmission power control method which concerns on this invention. It is a flowchart which shows the procedure of the aspect 7 of the transmission power control method which concerns on this invention. It is a figure for demonstrating Fractional transmission power control. It is a figure for demonstrating signaling of ULOI and ULHII. It is a figure for demonstrating ULCoMP.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a radio communication system having radio base station apparatuses and mobile terminal apparatuses according to an embodiment of the present invention.

The wireless communication system is a system to which, for example, E-UTRA (Evolved UTRA and UTRAN) is applied. The radio communication system includes a base station apparatus (eNB: eNodeB) 200 (200 ₁ , 200 ₂ ... 200 _l , l is an integer satisfying l> 0), and a plurality of mobile terminals (UE) communicating with the base station apparatus 200 100 _n (100 ₁ , 100 ₂ , 100 ₃ ,... 100 _n , n is an integer of n> 0). Base station apparatus 200 is connected to an upper station, for example, access gateway apparatus 300, and access gateway apparatus 300 is connected to core network 400. The mobile terminal 100 _n communicates with the base station apparatus 200 by E-UTRA in the cell 50 (50 ₁ , 50 ₂ ). Although the present embodiment shows two cells, the present invention can be similarly applied to three or more cells. In addition, since each mobile terminal (100 ₁ , 100 ₂ , 100 ₃ ,... 100 _n ) has the same configuration, function, and state, the following description will be given as the mobile terminal 100 _n unless otherwise specified. .

In a radio communication system, OFDM (Orthogonal Frequency Division Multiple Access) is applied to the downlink and SC-FDMA (Single Carrier Frequency Division Multiple Access) is applied to the uplink as the radio access scheme. OFDM is a multi-carrier transmission scheme that performs communication by dividing a frequency band into a plurality of narrow frequency bands (subcarriers) and mapping data to each subcarrier. SC-FDMA is a single carrier transmission scheme in which frequency bands are divided for each terminal, and a plurality of terminals use different frequency bands to reduce interference between terminals.

Here, communication channels in E-UTRA will be described.
For the downlink, a physical downlink shared channel (PDSCH) shared by each mobile terminal 100 _n and a physical downlink control channel (PDCCH) are used. The physical downlink control channel is also called a downlink L1 / L2 control channel. User data, that is, a normal data signal is transmitted through the physical downlink shared channel. In addition, downlink scheduling information (DL Scheduling Information), acknowledgment information (ACK / NACK), uplink scheduling grant (UL Scheduling Grant), TPC command (Transmission Power Control Command), and the like are transmitted by the physical downlink control channel. The downlink scheduling information includes, for example, the ID of a user who performs communication using a physical downlink shared channel, and information on the transport format of the user data, that is, data size, modulation scheme, retransmission control (HARQ: Hybrid ARQ) And downlink resource block allocation information.

The uplink scheduling grant includes, for example, the ID of a user who performs communication using the physical uplink shared channel, information on the transport format of the user data, that is, information on the data size and modulation scheme, This includes resource block allocation information, information related to uplink shared channel transmission power, and the like. Here, the uplink resource block corresponds to a frequency resource and is also called a resource unit.

Also, the delivery confirmation information (ACK / NACK) is delivery confirmation information related to the uplink shared channel. The content of the acknowledgment information is expressed by either an acknowledgment (ACK: Acknowledgement) indicating that the transmission signal has been properly received or a negative acknowledgment (NACK: Negative Acknowledgement) indicating that the transmission signal has not been properly received. Is done.

For the uplink, a physical uplink shared channel (PUSCH) shared by each mobile terminal 100 _n and a physical uplink control channel (PUCCH) are used. User data, that is, a normal data signal is transmitted through the physical uplink shared channel. Also, downlink quality information (CQI: Channel Quality Indicator) for use in shared physical channel scheduling processing and adaptive modulation and coding scheme (AMC) in the physical uplink control channel And acknowledgment information of the physical downlink shared channel are transmitted.

In the physical uplink control channel, in addition to CQI and delivery confirmation information, a scheduling request that requests resource allocation of an uplink shared channel (Scheduling Request), a release request (Release Request) in persistent scheduling, etc. May be sent. Here, the resource allocation of the uplink shared channel means that the base station apparatus may perform communication using the uplink shared channel in the subsequent subframe using the physical downlink control channel of a certain subframe. Means to notify the mobile terminal.

The mobile terminal 100 _n communicates with the optimal base station apparatus. In the example of FIG. 1, the

mobile terminal

₁₀₀ 1, 100 ₂ communicates with the base station apparatus 200 _1, the mobile terminal 100 ₃ is in communication with the base station apparatus 200 _2. At this time, the uplink transmission of the

mobile terminal

₁₀₀ 1, 100 _2, the interference to the base station apparatus 200 ₂ is a peripheral cell. This neighboring cell interference greatly varies because uplink mobile scheduling changes the mobile terminal to which transmission allocation is performed for each TTI (Transmission Time Interval) and for each RB (Resource Block).

Therefore, in order to reduce interference in the base station apparatus 200 _2, signals to be transmitted in uplink, an open loop due to propagation loss parameters and mobile terminal the radio base station apparatus notifies a relatively long period to measure The transmission power is controlled by a combination of the control and the closed loop control by the TPC command that the radio base station apparatus notifies in a relatively short cycle based on the communication status between the radio base station apparatus and the mobile terminal apparatus.

Further, the base station apparatus 200 _2, using ULOI, notifies reception interference level is high to the base station apparatus 200 _1. In the base station apparatus 200 _1, after receiving a ULOI, performs control to decrease the transmission power of the cell edge. In addition, the base station apparatus 200 ₁ uses ULHII to transmit resource block (RB) information to be allocated to the

mobile terminals

100 ₁ and 100 ₂ when the subordinate

mobile terminals

100 ₁ and 100 ₂ are located at the cell edge. It notifies the base station apparatus 200 ₂ cells in advance. The base station apparatus 200 ₂ in the peripheral cell that has received the ULHII performs control for performing frequency scheduling to avoid the RB.

Further, in this radio communication system, uplink multipoint reception (ULCoMP) can be applied as a further countermeasure against inter-cell interference. In this UL CoMP, for example, in the base station apparatus 200 ₁ is connected to the mobile terminal 100 _2, receives a desired signal from the mobile terminal 100 ₂ via the base station apparatus 200 ₂ in the neighboring cell. In other words, it receives a desired signal from the mobile terminal 100 ₂ in the

base station apparatus

₂₀₀ 1, 200 ₂ of the plurality of cells.

In the radio communication system shown in FIG. 1, inter-cell interference reduction technology (Fractional transmission power control, ULOI, ULHII) in the LTE system and ULCoMP can be used in combination, but ULCoMP is applied by applying the inter-cell interference reduction technology. When applied, the ULCoMP gain may be reduced as described above. Moreover, it is desirable to dynamically control whether ULCoMP is applied according to the propagation environment of the mobile terminal.

Therefore, as a result of intensive studies to solve the problems in using the inter-cell interference reduction technology in the LTE system and ULCoMP together, the present inventors have performed transmission power control when ULCoMP is not applied and when ULCoMP is applied. It has been found that the use of different transmission power control can prevent the reduction of the ULCoMP gain when ULCoMP is applied. In other words, when ULCoMP is applied, transmission power control for enhancing the effect of ULCoMP (transmission power control for increasing the gain of ULCoMP) is performed on the mobile terminal of the user at the cell edge. When ULCoMP is not applied, the mobile terminal of the user at the cell edge In contrast, transmission power control for reducing inter-cell interference is performed.

The use of transmission power control different from the transmission power control when ULCoMP is not applied when ULCoMP is applied is to change the transmission power control parameter when ULCoMP is applied and the transmission power control parameter when ULCoMP is not applied. Here, the transmission power control parameters are the attenuation coefficient α and the propagation loss PL of the α · PL term in the above equation (1) in the fractional transmission power control, the P ₀ _{_PUSCH} (j) in the above equation (1), and the TPC command. , A parameter used for transmission power control in inter-cell interference reduction technology in LTE systems such as ULOI and ULHII.

In the transmission power control method of the present invention, when transmission power control different from transmission power control when ULCoMP is not applied is used when ULCoMP is applied, a connection base station is applied to a mobile terminal to which ULCoMP is applied, if necessary. Notify that the device is ULCoMP-applied. Conversely, the mobile terminal applying ULCoMP is also notified that ULCoMP is not applied (exit from the ULCoMP state).

Application / non-application of ULCoMP is determined as follows, for example. As shown in FIG. 2, the propagation loss value PL ₁ with the base station apparatus 200 ₁ of the mobile terminal 100 ₁ and the connecting cell, the base station apparatus ₂₀₀ 2 small neighboring cell most propagation loss with the mobile terminal 100 ₁ (UL CoMP cooperation When the propagation loss difference PL _Diff (= PL ₂ −PL ₁ ) between the propagation loss value PL ₂ with the cell base station apparatus) is within a predetermined threshold XdB, the base station apparatus 200 of the connected cell ₁ applies ULCoMP to the mobile terminal 100 ₁ . Note that the propagation loss difference _{PL Diff,} the base station apparatus 200 ₁ is determined. In this case, the propagation loss value PL ₂ is acquired from the base station apparatus 200 ₂ by X2 interfaces. However, not limited to this method of obtaining the propagation loss value PL ₂ in the base station apparatus 200 _1, for example, it may be obtained from the mobile terminal 100 ₁ is connected to the base station apparatus 200 _1. Alternatively, a propagation loss difference _{PL Diff} calculated in the mobile terminal 100 _{_1,} may notify the _{PL Diff} base station apparatus 200 ₁ of the connected cell. The base station apparatus 200 ₂ for ULCoMP cooperation cell may be a base station apparatus 200 ₁ and the same base station apparatus connected cell. In addition, the determination of ULCoMP application / non-application is not limited to this, and can be changed as appropriate.

The ULCoMP application / non-application information is notified to the mobile terminal to which ULCoMP is applied, for example, by higher layer signaling via PDSCH. Specifically, “1” is signaled when switching from ULCoMP non-application to ULCoMP application, and “0” is notified when changing from ULCoMP application to ULCoMP non-application. In addition, ULCoMP application / non-application information is notified to a mobile terminal to which ULCoMP is applied, for example, by L1 / L2 signaling via PDCCH. Specifically, “1” is notified when ULCoMP is applied, and “0” is notified when ULCoMP is not applied (always). Note that the notification of ULCoMP application / non-application information is not limited to these, and can be changed as appropriate.

In the transmission power control method of the present invention, when ULCoMP is applied, there are the following modes in which transmission power control different from transmission power control when ULCoMP is not applied is used.

(Aspect 1)
In this aspect, the value of the attenuation coefficient α of the α · PL term in the above equation (1) in the fractional transmission power control is changed between when ULCoMP is applied and when ULCoMP is not applied (two attenuation coefficients are prepared). That is, the value of the attenuation coefficient α of fractional transmission power control can be set separately for a mobile terminal to which ULCoMP is applied. For a mobile terminal to which ULCoMP is applied, it is not necessary to lower the transmission power so as not to reduce the ULCoMP gain. For this reason, the effect of ULCoMP is enhanced by increasing the value of the attenuation coefficient α for the mobile terminal.

In this embodiment, as shown in FIG. 3, using the attenuation coefficient alpha ₁ of the mobile terminal 100 for ₁ ULCoMP application, the attenuation coefficient alpha ₂ for the mobile terminal 100 ₂ of ULCoMP non-application. The attenuation coefficients α ₁ and α ₂ may be broadcast via PBCH (Physical Broadcast Channel), individually notified by higher layer signaling via PDSCH, or by L1 / L2 signaling via PDCCH. You may notify separately. When the attenuation coefficients α ₁ and α ₂ are broadcast by PBCH, for example, the value of the attenuation coefficient α ₁ for ULCoMP application may be larger than the value of the attenuation coefficient α ₂ for ULCoMP non-application. α ₁ of the value may be a fixed 1.0. Further, when the attenuation coefficients α ₁ and α ₂ are notified by PDSCH or PDCCH, the same attenuation coefficient α ₁ may be uniformly notified to all the ULCoMP-applied mobile terminals, and different attenuation coefficients for each mobile terminal. α ₁ may be notified. When the attenuation coefficients α ₁ and α ₂ are broadcast by PBCH, ULCoMP application / non-application information needs to be notified to the mobile terminal as described above.

(Aspect 2)
In this aspect, the value of the propagation loss PL of the α · PL term in the above equation (1) in the fractional transmission power control is changed between when ULCoMP is applied and when ULCoMP is not applied. In the fractional transmission power control, the transmission power is weighted by the attenuation coefficient α to the propagation loss value PL ₁ between the mobile terminal 100 ₁ and the base station apparatus 200 ₁ of the connected cell. Therefore, to apply the PL _1, a composite value _{PL CoMP} obtained by the propagation loss value PL ₂ with the base station apparatus 200 ₂ of the mobile terminal 100 ₁ and ULCoMP cooperation cell. When a value larger than PL ₁ is applied as PL _CoMP , the value of the α · PL term in the above equation (1) becomes large, so that the ULCoMP effect can be enhanced. Alternatively, when a value smaller than PL ₁ is applied as the combined value PL _CoMP , it is possible to suppress the neighboring cell interference given by the ULCoMP-applied mobile terminal 100 ₁ .

In this embodiment, as shown in FIG. 4, obtaining the composite value (Synthesis value of the propagation _{loss) PL CoMP} by using the propagation loss value PL ₂ with the base station apparatus 200 ₂ of the mobile terminal 100 ₁ and ULCoMP cooperation cells . Mobile terminal 100 ₁ by using the composite value _{PL CoMP} determine the transmission power. For example, as PL _CoMP = (PL ₁ + PL ₂ ) / 2, the transmission power of the mobile terminal 100 ₁ to which ULCoMP is applied may be increased by setting the value larger than the value PL ₁ applied in the normal transmission power calculation, and vice versa. And PL _CoMP = PL ₁ · PL ₂ / (PL ₁ + PL ₂ ) (calculated by correcting to true value and finally converted to dB), a value smaller than the value PL ₁ applied in normal transmission power calculation Although the transmission power decreases, the transmission power may be set to an appropriate transmission power considering the neighboring cell interference. In addition, there is no restriction _| limiting in particular about how to obtain _| require synthetic value PL _CoMP . Further, in this aspect, as described above, it is necessary to notify the mobile terminal of ULCoMP application / non-application information.

(Aspect 3)
In this aspect, the values of the propagation loss PL and the propagation loss difference PL _Diff of the mobile terminal applied to the transmission power control by the base station apparatus are changed between when ULCoMP is applied and when ULCoMP is not applied. In the base station apparatus, the target received power _PRx or target received SINR (T _SINR ) of the mobile terminal is set using the propagation loss difference PL _Diff between the mobile terminal and the base station apparatus of the neighboring cell having the smallest propagation loss. .
P _Rx = Px + β · PL _Diff + γ Equation (2)
Px: received power reference value, β: propagation loss difference correction coefficient, γ: offset T _SINR = Tx + β · PL _Diff + γ Equation (3)
Tx: target reception SINR reference value, β: propagation loss difference correction coefficient, γ: offset

Here, the propagation loss difference correction coefficient β can be described from the target received power (P _Rx ), the target received SINR (T _SINR ), and the propagation loss difference PL _Diff as shown in FIG. In the relationship shown in FIG. 5, for the purpose of suppressing inter-cell interference, the target received power and the target received SINR are set to be small for the mobile terminal existing at the cell edge. That is, if the propagation loss difference (PL _Diff ) is large, the user is present near the base station apparatus. If the propagation loss is small, the user is considered to be present at the cell edge. The target received power and target received SINR of the user's mobile terminal are relatively increased, and the target received power and target received SINR of the user's mobile terminal at the cell edge are relatively decreased. The slope of the primary characteristic line of such a relationship is β. For example, in consideration of consistency with Equation (1) of Fractional transmission power control, β = 1−α can be set, but the present invention is not limited to this.

In this aspect, PL _Diff = PL ₂ -PL ₁ is set to, for example, PL _Diff = PL ₃ -PL _CoMP for the ULCoMP-applied mobile terminal. _{Here, PL CoMP} is the same as _{PL CoMP} in aspects 2. Further, the propagation loss value PL ₃ represents the propagation loss between the base station apparatus small neighboring cell most propagation loss except ULCoMP cooperation cell. By changing PL _Diff in this way, it is possible to set a large target reception power and target reception SINR for a ULCoMP-applied mobile terminal that mainly exists at the cell edge, and it is possible to enhance the effect of ULCoMP. Note that _setting PL _CoMP to be a value smaller than the conventional PL ₁ is advantageous from the viewpoint of reliably increasing the target reception power and the target reception SINR.

The base station apparatus, for example, calculates the difference between the measured received power and _PRx obtained by Equation (2), or the difference between the measured received SINR and T _SINR obtained by Equation (3). , It is reflected in the TPC command and P _{0_PUSCH} and notified to the mobile terminal in a closed loop. Therefore, in this aspect, transmission power control is performed with the target reception power or target reception SINR obtained by changing PL _Diff . In this aspect, it is not necessary to notify the mobile terminal of ULCoMP application / non-application information.

(Aspect 4)
In this aspect, the transmission power of fractional transmission power control is changed between when ULCoMP is applied and when ULCoMP is not applied. In a mobile terminal to which ULCoMP is applied, the final transmission power is set from the transmission power obtained from the propagation loss with the base station apparatus of the connected cell and the transmission power obtained from the propagation loss with the base station apparatus of the ULCoMP cooperating cell. . In fractional transmission power control in the LTE system, transmission power P ₁ calculated from the propagation loss value PL ₁ for the connected cell is applied. In this embodiment, as shown in FIG. 6, the transmission power _{P 1} which is calculated from the propagation loss value PL ₁ with the base station apparatus 200 ₁ of the mobile terminal 100 ₁ and the connecting cell, the mobile terminal 100 ₁ and ULCoMP cooperation cells of (in general, becomes a value greater than _{P 1)} transmit power _{P 2} is calculated from the propagation loss value PL ₂ with the base station apparatus 200 ₂ as the final transmission power _{P CoMP} considering. Thereby, since the transmission power value in Fractional transmission power control at the time of ULCoMP application becomes large, the effect of ULCoMP can be enhanced.

In this aspect, for example, when ULCoMP is applied, in the mobile terminal 100 ₁ , the transmission power P ₁ calculated using the propagation loss value PL ₁ with the base station apparatus 200 ₁ of the connected cell, and the base station of the ULCoMP cooperating cell 200 ₂ and the propagation loss value PL ₂ and used calculated transmit power _{P 2} transmit power the average value of the _{P CoMP} (synthesis value of the transmission _{_{_{power: P CoMP = (P 1 +}}} P 2) / 2) as well The transmission power P ₂ may be used as it is as the transmission power P _CoMP (P _CoMP = P ₂ ). Further, in this aspect, as described above, it is necessary to notify the mobile terminal of ULCoMP application / non-application information.

(Aspect 5)
In this aspect, the range or the number of bits of the transmission power control command (TPC command) in the UL scheduling grant is changed between when ULCoMP is applied and when ULCoMP is not applied. That is, the range or the number of bits of the transmission power control command (TPC command) in the UL scheduling grant is expanded for the mobile terminal to which ULCoMP is applied. In this way, by expanding the range of the TPC command, it is possible to respond quickly to changes in the target received power mainly at the time of ULCoMP application switching.

In this aspect, for example, as shown in FIG. 7, the base station apparatus 200 ₁ of the connected cell sends a TPC command of 3 bits or more with UL scheduling grant to the mobile terminal 100 ₁ to which ULCoMP is applied, and ULCoMP non- to the mobile terminal 100 ₂ applications, 2-bit TPC commands in UL scheduling grant ({-1,0, + 1, + 3} dB) to send. 3-bit TPC commands are {-5, -3, -1, 0, +1, +3, +5, +7} dB, {-3, -1, 0, +1, +3, +5, +7, +9} dB, etc. It is.

Further, the base station apparatus 200 ₁ of the connected cell to the mobile terminal 100 ₁ of ULCoMP application, sends a TPC command of an enlarged range by UL scheduling grant, the mobile terminal 100 ₂ of ULCoMP non-application, UL scheduling A normal range TPC command ({−1, 0, +1, +3} dB) is sent by grant. The TPC command whose range is expanded is {0, +1, +3, +5} dB, {0, +2, +4, +6} dB, etc. (2 bits). In this embodiment, it is necessary to determine the nature of the TPC command in the mobile terminal 100 _1. Therefore, the contents of the 3-bit TPC command and the expanded TPC command are individually notified by higher layer signaling as, for example, TPC-Index. In addition, as described above, ULCoMP application / non-application information needs to be notified to the mobile terminal, but the TPC-Index indicating the 3-bit TPC command or the expanded TPC command is notified by higher layer signaling. In this case, the mobile terminal may recognize that ULCoMP is applied regardless of the presence / absence of the ULCoMP application / non-application information.

(Aspect 6)
In this aspect, when a change occurs in a ULCoMP-applied mobile terminal (when an increase or decrease occurs in a mobile terminal to which ULCoMP is applied, such as ULCoMP application ⇔ ULCoMP not applied), the base station apparatus updates ULOI and ULHII. . ULOI and ULHII in the LTE system impose restrictions on transmission power control and scheduling of neighboring cells, and when ULCoMP is applied, the restriction may reduce the effect of ULCoMP, particularly immediately after state transition. . Therefore, in this aspect, when ULCoMP is applied, ULOI and ULHII signaling is updated. Thereby, even immediately after state transition, the effect of ULCoMP at the time of applying ULCoMP can be enhanced.

In this embodiment, as shown in FIG. 8, if the change to the mobile terminal 100 ₁ of UL CoMP application has occurred, (when the mobile terminal is increased to apply the UL CoMP) where when a UL CoMP non-application → UL CoMP applied When the contents of ULOI and ULHII change, the change contents are notified to the base station apparatus of the neighboring cell. That is, the notification from the base station apparatus 200 ₁ of the connected cell, to the base station apparatus 200 ₂ which became a neighboring cell to ULCoMP cooperation cell, if the restrictions ULHII becomes unnecessary, the ULHII the contents of restriction release To do. The notification from the base station apparatus 200 ₂ which became a neighboring cell to ULCoMP cooperation cell, the base station apparatus 200 ₁ of the connected cell, if the restrictions ULOI becomes unnecessary, the ULOI the contents of restriction release To do. Alternatively, the base station apparatus 200 ₂ thong became ULCoMP cooperation cell, in the present embodiment does not need to notify the information of ULCoMP application / non-application to mobile terminal. In the above description, the case where both ULOI and ULHII are used in the wireless communication system has been described. However, the present invention is not limited to this, and the system may use either ULOI or ULHII. .

(Aspect 7)
In this aspect, when ULCoMP is applied to a mobile terminal that applies radio-based Overload Indicator (OLI) to transmission power control, the mobile terminal is notified of resetting the OLI restriction. In this case, it is assumed that the base station apparatus transmits an OLI directly (on a radio basis) to the mobile terminals under the neighboring cells, and the mobile terminal performs transmission power control according to the OLI. Thereby, similarly to aspect 6, the effect of ULCoMP at the time of applying ULCoMP can be enhanced even immediately after state transition. Note that the base station apparatus sends an OLI directly (on a radio basis) to a mobile terminal under a neighboring cell, and the mobile terminal has already proposed the transmission power control according to the OLI in WO2008 / 044528. is doing. All this content is included here.

In this aspect, as shown in FIG. 9, when a change occurs in the ULCoMP-applied mobile terminal 100 ₁ communicating with the base station apparatus 200 ₁ of the connected cell, the ULCoMP non-application → ULCoMP application is adopted here. case, the mobile terminal 100 ₁ to the base station apparatus 200 ₂ which became a neighboring cell to ULCoMP cooperation cell, transmits a radio signal indicating that releasing the OLI (reset). Here, the radio signals to the effect that releasing the OLI (reset), for example, such as a wireless signal to the offset term of the transmission power for the mobile terminal 100 ₁ to zero, and the like. In this aspect, it is not necessary to notify the mobile terminal of ULCoMP application / non-application information.

FIG. 10 is a block diagram showing a schematic configuration of the mobile terminal apparatus according to the embodiment of the present invention.
A mobile terminal 100 _n illustrated in FIG. 10 mainly includes an antenna 102, an amplifier unit 104, a transmission / reception unit 106, a baseband signal processing unit 108, a call processing unit 110, and an application unit 112.

In the mobile terminal 100 _{n having} such a configuration, for downlink data, the radio frequency signal received by the antenna 102 is corrected by the amplifier unit 104 and the received power is corrected to a constant power under AGC (Auto Gain Control). So that it is amplified. The amplified radio frequency signal is frequency-converted into a baseband signal by the transmission / reception unit 106. The baseband signal is subjected to predetermined processing (error correction, decoding, etc.) by the baseband signal processing unit 108 and then sent to the call processing unit 110 and the application unit 112. The call processing unit 110 manages communication with the base station apparatus 200, and the application unit 112 performs processing related to a layer higher than the physical layer and the MAC layer.

Uplink data is input from the application unit 112 to the baseband signal processing unit 108. The baseband signal processing unit 108 performs retransmission control processing, scheduling, transmission format selection, channel coding, and the like, and transfers the result to the transmission / reception unit 106. The transmission / reception unit 106 frequency-converts the baseband signal output from the baseband signal processing unit 108 into a radio frequency signal. The frequency-converted signal is then amplified by the amplifier unit 104 and transmitted from the antenna 102.

FIG. 11 is a block diagram showing a configuration of a baseband signal processing unit in the mobile terminal apparatus shown in FIG.
The baseband signal processing unit 108 includes a layer 1 processing unit 1081, a MAC (Medium Access Control) processing unit 1082, an RLC (Radio Link Control) processing unit 1083, an ULCoMP notification signal reception processing unit 1084, and an α reception processing unit. 1085, a TPC command reception processing unit 1086, an OLI reception processing unit 1087, a PL _CoMP calculation unit 1088, and a transmission power setting unit 1089. The α reception processing unit 1085, the TPC command reception processing unit 1086, and the OLI reception processing unit 1087 are transmission power control parameter reception units that receive transmission power control parameters transmitted from the base station apparatus.

The layer 1 processing unit 1081 mainly performs processing related to the physical layer. For example, the layer 1 processing unit 1081 performs channel decoding, discrete Fourier transform (DFT: Discrete Fourier Transform), frequency demapping, inverse fast Fourier transform (IFFT: Inverse Fast Fourier Transform) on a signal received on the downlink. Processing such as data demodulation. Further, the layer 1 processing unit 1081 performs processing such as channel coding, data modulation, frequency mapping, and inverse fast Fourier transform (IFFT) on a signal transmitted on the uplink.

The MAC processing unit 1082 performs retransmission control (HARQ) at the MAC layer for a signal received on the downlink, analysis of downlink scheduling information (specification of PDSCH transmission format, identification of PDSCH resource block), and the like. Further, the MAC processing unit 1082 performs processing such as MAC retransmission control for signals transmitted on the uplink, analysis of uplink scheduling information (specification of PUSCH transmission format, specification of PUSCH resource block), and the like.

The RLC processing unit 1083 performs packet division, packet combination, retransmission control in the RLC layer, etc. on packets received on the downlink / packets transmitted on the uplink.

The ULCoMP notification signal reception processing unit 1084 receives the ULCoMP notification signal notified from the base station apparatus of the connected cell, and determines the content of the ULCoMP notification signal (ULCoMP application / ULCoMP non-application). Information on the ULCoMP notification signal is sent to the transmission power setting unit 1089 and also sent to the PL _CoMP calculation unit 1088, the TPC command reception processing unit 1086, or the α reception processing unit 1085. The ULCoMP notification signal is transmitted on the downlink PDSCH or PDCCH.

The α reception processing unit 1085 receives a signal of an attenuation coefficient α, which is a parameter used for transmission power control, notified from the base station apparatus, and determines the content of the signal. The information on the attenuation coefficient α is sent to the transmission power setting unit 1089. The α reception processing unit 1085 receives the attenuation coefficient α ₁ when ULCoMP is applied when ULCoMP is applied (when receiving information of the ULCoMP notification signal), and receives the attenuation coefficient α ₂ when ULCoMP is not applied when ULCoMP is not applied. To do. The α reception processing unit 1085 sends the attenuation coefficient α ₁ and the attenuation coefficient α ₂ to the transmission power setting unit 1089.

The TPC command reception processing unit 1086 receives the TPC command notified from the base station apparatus, and determines the content of the TPC command. The information of the TPC command is sent to the transmission power setting unit 1089. The TPC command reception processing unit 1086 receives a TPC command (for example, a 3-bit TPC command) when ULCoMP is applied when ULCoMP is applied (when receiving information of a ULCoMP notification signal), and when ULCoMP is not applied. The TPC command (2-bit TPC command) is received. The TPC command reception processing unit 1086 sends the TPC command to the transmission power setting unit 1089.

The OLI reception processing unit 1087 receives the OLI notified from the base station apparatus in the neighboring cell, and determines the contents of the OLI (with OLI restriction, OLI restriction release). The OLI information is sent to the transmission power setting unit 1089. The OLI reception processing unit 1087 receives an OLI restriction release OLI when ULCoMP is applied, and receives an OLI restricted OLI (normal OLI) when ULCoMP is not applied.

The PL _CoMP calculation unit 1088 calculates a propagation loss value used for transmission power control. The PL _CoMP information is sent to the transmission power setting section 1089. The PL _CoMP calculating unit 1088, when applying ULCoMP (when receiving information of the ULCoMP notification signal), the propagation loss PL ₁ between the own device and the base station device of the connected cell, and the base of the own device and the ULCoMP cooperating cell. PL _CoMP is calculated using the propagation loss PL ₂ between the station apparatus (base station apparatus having the smallest propagation loss with respect to the own apparatus). The PL _CoMP calculation unit 1088 sends PL _CoMP to the transmission power setting unit 1089. In this case, the propagation loss PL ₁ is the propagation loss obtained by the own device, the propagation loss PL ₂ is the propagation loss obtained by the own device, or the base station device of the connected cell from the base station device of the ULCoMP cooperating cell through the X2 interface. _Is transmitted to the PL _CoMP calculating unit 1088. When ULCoMP is not applied, the propagation loss PL ₁ is sent to the transmission power setting unit 1089.

The transmission power setting unit 1089 sets transmission power using transmission power control parameters. That is, the transmission power setting unit 1089 sets transmission power using a transmission power control parameter that is different from the transmission power control parameter when ULCoMP is not applied when ULCoMP is applied, and when ULCoMP is not applied. The transmission power is set using the transmission power control parameter at the time of application.

The transmission power setting unit 1089 uses the attenuation coefficient α ₁ at the time of applying ULCoMP output from the α reception processing unit 1085 at the time of applying ULCoMP (when receiving the information of the ULCoMP notification signal) to the above equation (1). based sets the transmission power, sets the transmission power based on the equation (1) using the attenuation coefficient alpha ₂ of UL CoMP non-application time during non-application of UL CoMP (embodiment 1).

The transmission power setting unit 1089, when applying ULCoMP (when receiving information of the ULCoMP notification signal), instead of the propagation loss PL ₁ with the connected base station apparatus as a propagation loss when applying ULCoMP. , The transmission power is set based on the above equation (1) using the propagation loss PL _CoMP output from the PL _CoMP calculation unit 1088, and is connected as a propagation loss when ULCoMP is not applied when ULCoMP is not applied. The transmission power is set based on the above equation (1) using the propagation loss PL ₁ with the base station apparatus (Aspect 2).

Based on the above equation (1), transmission power setting section 1089 uses propagation loss PL ₁ with the connected base station apparatus when ULCoMP is applied (when information on the ULCoMP notification signal is received). the transmission is determined power _{P 1,} the transmission power _{P CoMP} using a transmission power _{P 2} obtained based on the equation (1) using the propagation loss PL ₂ between the base station apparatus cooperation cells ULCoMP Is set (mode 4).

The transmission power setting unit 1089 has a larger number of bits and a range than the TPC command output from the TPC command reception processing unit 1086 and output from the TPC command reception processing unit 1086 when ULCoMP is applied (when information of the ULCoMP notification signal is received). The transmission power is set by the TPC command, and the transmission power is set by the TPC command output from the TPC command reception processing unit 1086 when ULCoMP is not applied when ULCoMP is not applied (mode 5).

FIG. 12 is a block diagram showing a schematic configuration of the radio base station apparatus according to the embodiment of the present invention.
The base station apparatus 200 _n shown in FIG. 12 mainly includes an antenna 202, an amplifier unit 204, a transmission / reception unit 206, a baseband signal processing unit 208, a call processing unit 210, and a transmission path interface 212. Yes.

In the base station apparatus 200 _{n having} such a configuration, the uplink data is amplified so that the radio frequency signal received by the antenna 202 is corrected by the amplifier unit 204 and the received power is corrected to a constant power under the AGC. Is done. The amplified radio frequency signal is frequency converted into a baseband signal in the transmission / reception unit 206. The baseband signal is subjected to predetermined processing (error correction, decoding, etc.) by the baseband signal processing unit 208 and then transferred to an access gateway device (not shown) via the transmission path interface 212. The access gateway device is connected to the core network and manages each mobile terminal. For the uplink, the received SINR and interference level of the radio frequency signal received by the base station apparatus 200 are measured based on the uplink baseband signal.

The call processing unit 210 transmits / receives a call processing control signal to / from a radio control station of the host device, and manages the state of the base station device 200 and allocates resources. Note that the processing in the layer 1 processing unit 2081 and the MAC processing unit 2082 is performed based on the communication state between the base station apparatus 200 and the mobile station apparatus 100 set in the call processing unit 210.

Downlink data is input from the host device to the baseband signal processing unit 208 via the transmission path interface 212. The baseband signal processing unit 208 performs retransmission control processing, scheduling, transmission format selection, channel coding, and the like, and transfers the result to the transmission / reception unit 206. The transmission / reception unit 206 converts the frequency of the baseband signal output from the baseband signal processing unit 208 into a radio frequency signal. The frequency-converted signal is then amplified by the amplifier unit 204 and transmitted from the antenna 202.

FIG. 13 is a block diagram showing a configuration of a baseband signal processing unit in the radio base station apparatus shown in FIG.
The baseband signal processing unit 208 includes a layer 1 processing unit 2081, a MAC processing unit 2082, an RLC processing unit 2083, a propagation loss difference calculation unit 2084, an ULCoMP processing unit 2085, an OI processing unit 2086, and an HII processing unit. 2087, an OLI processing unit 2088, and a transmission power control unit 2089 are mainly configured.

The layer 1 processing unit 2081 mainly performs processing related to the physical layer. For example, the layer 1 processing unit 2081 performs processing such as channel decoding, discrete Fourier transform (DFT), frequency demapping, inverse fast Fourier transform (IFFT), and data demodulation on a signal received on the uplink. Also, the layer 1 processing unit 2081 performs processing such as channel coding, data modulation, frequency mapping, and inverse fast Fourier transform (IFFT) on a signal transmitted on the downlink.

The MAC processing unit 2082 performs processing such as retransmission control in the MAC layer for a signal received in the uplink, scheduling for the uplink / downlink, selection of a PUSCH / PDSCH transmission format, selection of a PUSCH / PDSCH resource block, and the like. .

The RLC processing unit 2083 performs packet division, packet combination, retransmission control in the RLC layer, etc. on packets received on the uplink / packets transmitted on the downlink.

The propagation loss difference calculation unit 2084 calculates a propagation loss difference between the mobile terminal and the base station apparatus of the peripheral cell of the mobile terminal (base station apparatus candidate of the ULCoMP cooperative cell). That is, the propagation loss between the connected mobile terminal and a plurality of base station apparatuses in the neighboring cells of the mobile terminal is calculated, and the minimum propagation loss is extracted from the propagation loss. The propagation loss difference calculation unit 2084 sends this minimum propagation loss information to the ULCoMP processing unit 2085. At this time, the propagation loss difference calculation unit 2084 also sends information on the base station device (base station device of the ULCoMP cooperating cell) having the minimum propagation loss to the ULCoMP processing unit 2085.

The ULCoMP processing unit 2085 determines whether or not the ULCoMP is applied to the mobile terminal based on the calculation result of the propagation loss difference calculation unit 2084. ULCoMP processing unit 2085, a propagation loss PL ₁ between the own apparatus and the mobile terminal, the mobile terminal and the propagation loss PL ₂ between the small base station apparatus most propagation loss with respect to this mobile terminal, during the When the difference (PL ₂ −PL ₁ ) is within a predetermined range, it is determined that ULCoMP is applied to the mobile terminal. The ULCoMP processing unit 2085 determines that ULCoMP is not applied to the mobile terminal when the difference (PL ₂ −PL ₁ ) is not within a predetermined range. The ULCoMP processing unit 2085 sends the ULCoMP application / non-application determination result to the OI processing unit 2086, the HII processing unit 2087, or the OLI processing unit 2088 and also sends it to the transmission power control unit 2089.

Also, the ULCoMP processing unit 2085 notifies the mobile terminal of ULCoMP application / non-application information. This information is notified to the mobile terminal to which ULCoMP is applied via PBCH, PDSCH or PDCCH.

When the base station apparatus is a base station apparatus of a ULCoMP cooperating cell and the number of mobile terminals to which ULCoMP is applied is changed, the OI processing unit 2086 generates a ULOI when the contents of the ULOI change. Then, this ULOI is notified to the base station apparatus of the connected cell (mode 6). The OI processing unit 2086 generates a ULOI restriction cancellation OI when a change occurs in the contents of the ULOI when ULCoMP is applied, and notifies this OI to the base station apparatus of the connected cell via the X2 interface. Further, the OI processing unit 2086 generates a ULOI-restricted OI if necessary when ULCoMP is not applied, and notifies the OI to the base station apparatus of the connected cell via the X2 interface. In this case, the base station apparatus of the ULCoMP cooperating cell is notified of ULCoMP application / non-application information from the base station apparatus of the connected cell via the X2 interface.

The HII processing unit 2087 generates ULHII and notifies the ULHII to the base station apparatus of the ULCoMP cooperating cell. The HII processing unit 2087 changes the contents of the HII when ULCoMP is applied (when the ULCoMP application determination result is received from the ULCoMP processing unit 2085), that is, when the number of mobile terminals to which ULCoMP is applied is changed. Is generated, the HII of the HII restriction release is generated, and this HII is notified to the base station apparatus of the ULCoMP cooperating cell via the X2 interface (Aspect 6). In addition, the HII processing unit 2087 generates an HII restricted HII if necessary when the ULCoMP is not applied (when the ULCoMP non-application determination result is received from the ULCoMP processing unit 2085). Via the base station apparatus of the ULCoMP cooperating cell.

The OLI processing unit 2088 generates an OLI and notifies the mobile terminal communicating with the base station apparatus of the connected cell (neighboring cell) (mode 7). When the base station apparatus is a base station apparatus of a ULCoMP cooperating cell, the OLI processing unit 2088 generates an OLI for releasing the OLI restriction, and directly notifies the mobile terminal communicating with the base station apparatus of the connected cell. To do. In addition, when ULCoMP is not applied, the OLI processing unit 2088 generates an OLI-restricted OLI as needed, and directly notifies the mobile terminal communicating with the base station apparatus of the connected cell. In this case, the base station apparatus of the ULCoMP cooperating cell is notified of ULCoMP application / non-application information from the base station apparatus of the connected cell via the X2 interface.

The transmission power control unit 2089 performs transmission power control when ULCoMP is applied when ULCoMP is applied, and performs transmission power control when ULCoMP is not applied when ULCoMP is not applied.

14 is a block diagram showing a configuration of a transmission power control unit in the baseband signal processing unit shown in FIG.
The transmission power control unit 2089 mainly includes an α processing unit 20891, a PL _CoMP calculation unit 20892, and a TPC command processing unit 20893.

The α processing unit 20891 generates an attenuation coefficient α used for transmission power control. An attenuation coefficient α ₁ when ULCoMP is applied and an attenuation coefficient α ₂ when ULCoMP is not applied are generated. Further, the α processing unit 20891 notifies the attenuation coefficients α ₁ and α ₂ to the ULCoMP-applied mobile terminal via the PDSCH or PDCCH, or broadcasts them via the PBCH (Aspect 1).

The PL _CoMP calculator ₂₀₈₉₂ calculates a propagation loss value used for closed-loop transmission power control. The PL _CoMP calculating unit 20892, when applying ULCoMP (when receiving the determination result of ULCoMP application), the propagation loss PL ₁ between the own device (base station device of the connected cell) and the mobile terminal, the mobile terminal and the ULCoMP PL _CoMP is calculated using the propagation loss PL ₂ with the base station apparatus of the cooperation cell (mode 2). In this case, the propagation loss PL ₁ is a propagation loss acquired from the mobile terminal and is sent to the PL _CoMP calculation unit 20892, and the propagation loss PL ₂ is acquired from the mobile terminal or the base station apparatus of the ULCoMP cooperating cell through the X2 interface. And sent to the PL _CoMP calculation unit 20892. When ULCoMP is not applied, these propagation losses PL ₁ and PL ₂ are sent to the TPC command processing unit 20893.

The TPC command processing unit 20893 uses the propagation loss difference (PL _Diff ), the received power reference value (Px), the propagation loss difference correction coefficient (β), the offset (γ), and the target received SINR reference value (Tx). The target received power (P _Rx ) or target received SINR (T _SINR ) is set, and the difference between the measured received power and the target received power, or between the measured received SINR and the target received SINR. A TPC command is generated from the difference between the two.

In the TPC command processing unit 20893, when ULCoMP is applied (when the determination result of ULCoMP application is received), as a propagation loss difference (PL _Diff ), the propagation loss PL ₁ , the base station apparatus and the mobile terminal of the ULCoMP cooperating cell, The propagation loss difference obtained by using the propagation loss PL _CoMP obtained from the propagation loss PL2 between the _two is used (mode 3). For example, when ULCoMP is applied, the propagation loss difference (PL _Diff ) is set as PL _Diff = PL ₃ −PL _CoMP . Here, the propagation loss PL ₃ represents the propagation loss between the base station apparatus and the mobile terminal of the neighboring cell having the smallest propagation loss except for the ULCoMP cooperative cell. Note that the propagation loss PL ₁ is acquired from the mobile terminal, and PL ₂ and PL ₃ are acquired from the mobile terminal or the peripheral base station apparatus through the X2 interface.

The TPC command processing unit 20893 makes the transmission power control amount when ULCoMP is applied larger than the transmission power control amount when ULCoMP is not applied (mode 4). In the TPC command processing unit 20893, when ULCoMP is applied (when the determination result of ULCoMP application is received), a TPC command having a larger number of bits and range than the TPC command when ULCoMP is not applied is generated, and ULCoMP is not applied. Sometimes, a TPC command is generated when ULCoMP is not applied. The TPC command generated in this way is transmitted to the mobile terminal via the PDCCH.

In a wireless communication system having the above configuration, the base station apparatus 200 ₁ in which the mobile terminal 100 ₁ is connected, the propagation loss PL ₁ between the mobile terminal 100 _1, the mobile terminal 100 ₁ and the mobile terminal 100 ₁ when the propagation loss PL ₂ between the small base station apparatus 200 ₂ most propagation loss, the difference _(PL 2 -PL ₁₎ between in a predetermined range for the mobile terminal 100 ₁ Applying ULCoMP, transmitting ULCoMP transmission power control parameters when ULCoMP is applied to the mobile terminal 100 ₁ , transmitting ULCoMP non-application transmission power control parameters to the mobile terminal 100 ₁ when ULCoMP is not applied, in the mobile terminal 100 ₁ receives the transmission power control parameter transmitted from the base station apparatus 200 _1, the ULCoMP During use, it sets the transmission power using different transmission power control parameter and the transmission power control parameter during non-application of UL CoMP.

According to such a transmission power control method, since transmission power control at the time of applying ULCoMP is adopted at the time of applying ULCoMP, the conventional inter-cell interference reduction technology and ULCoMP can be used together without reducing the gain of ULCoMP. Can do.

Note that the configurations of the radio base station apparatus and the mobile terminal apparatus are illustrated so as to be able to deal with all aspects for the sake of explanation. Therefore, a block that is not used in each aspect may not be provided in the apparatus according to the aspect.

Next, the processing procedure of each aspect in the transmission power control method of this invention is demonstrated.
FIG. 15 is a flowchart showing an example of a procedure regarding notification of ULCoMP application / non-application of the transmission power control method according to the present invention.

First, in the ULCoMP processing unit 2085 of the base station apparatus, the difference between the propagation loss between the mobile terminal and the base station apparatus of the connected cell and the propagation loss between the mobile terminal and the base station apparatus of the neighboring cell is within a predetermined range. It is determined whether it is within (within X dB) (ST1).

When the propagation loss difference is not less than X dB, if the mobile terminal has already been the target of ULCoMP (ST2), the ULCoMP processing unit 2085 of the base station apparatus excludes the mobile terminal from the ULCoMP target, and to that effect To the mobile terminal (ST4). On the other hand, when the propagation loss difference is within X dB, if the mobile terminal is not already the target of ULCoMP (ST3), the ULCoMP processing unit 2085 of the base station apparatus adds the mobile terminal to the target of ULCoMP. Then, this is notified to the mobile terminal (ST5). For notification to the mobile terminal, higher layer signaling such as PDSCH is used.

FIG. 16 is a flowchart showing another example of a procedure related to ULCoMP application / non-application notification of the transmission power control method according to the present invention.

First, in the ULCoMP processing unit 2085 of the base station apparatus, the difference between the propagation loss between the mobile terminal and the base station apparatus of the connected cell and the propagation loss between the mobile terminal and the base station apparatus of the neighboring cell is within a predetermined range. It is determined whether it is within (within X dB) (ST11).

When the propagation loss difference is not within X dB, if the mobile terminal has already been the target of ULCoMP (ST12), the ULCoMP processing unit 2085 of the base station apparatus excludes the mobile terminal from the ULCoMP target (ST14). The mobile terminal is notified that it is not a ULCoMP target (ST15). On the other hand, when the propagation loss difference is within X dB, if the mobile terminal is not already the target of ULCoMP (ST13), the ULCoMP processing unit 2085 of the base station apparatus adds the mobile terminal to the target of ULCoMP. (ST16) The mobile terminal is notified that it is a ULCoMP target (ST17). For notification to the mobile terminal, L1 / L2 signaling such as PDCCH is used.

FIG. 17 is a flowchart showing an example of the procedure of the aspect 1 of the transmission power control method according to the invention.
The α processing unit 20891 of the base station apparatus generates an attenuation coefficient α ₂ for a normal mobile terminal (a mobile terminal not applying ULCoMP) and an attenuation coefficient α ₁ for a mobile terminal applying ULCoMP, and generates two types of attenuation. The coefficient is broadcast via PBCH (ST21).

In the mobile terminal, it is determined whether or not the device itself is ULCoMP-applied (ST22), and if it is recognized that the device itself is ULCoMP-applied, the transmission power setting section 1089 determines that ULCoMP is applied. The transmission power is set based on the above equation (1) using the attenuation coefficient α ₁ for the applied mobile terminal (ST23). On the other hand, if the own apparatus does not apply ULCoMP, transmission power setting section 1089 sets transmission power based on the above equation (1) using normal mobile terminal attenuation coefficient α ₂ (ST24).

FIG. 18 is a flowchart showing another example of the procedure of the aspect 1 of the transmission power control method according to the invention.
Mobile terminal determines whether the mobile terminal is applied UL CoMP (ST31), if not the mobile terminal is UL CoMP applied, the transmission power setting unit 1089 uses the broadcast attenuation coefficient alpha ₂ of the normal for the mobile terminal Then, the transmission power is set based on the above equation (1) (ST33). On the other hand, the mobile terminal when a mobile terminal that is applied ULCoMP, the base station apparatus notifies the individual attenuation coefficient alpha ₁ to the mobile terminal (ST32). For this notification, higher layer signaling such as PDSCH or L1 / L2 signaling such as PDCCH is used. Then, in the mobile terminal, transmission power setting section 1089 sets transmission power based on the above equation (1) using attenuation coefficient α ₁ notified individually (ST34).

FIG. 19 is a flowchart showing the procedure of the aspect 2 of the transmission power control method according to the invention.
In the mobile terminal, it is determined whether or not the device itself is ULCoMP-applied and recognized (ST41), and if the device recognizes that the device is ULCoMP-applied, the PL _CoMP calculation unit of the mobile terminal 1088 calculates the combined propagation loss PL _CoMP , and the transmission power setting section 1089 sets the transmission power based on the above equation (1) using the PL _CoMP (ST42). On the other hand, if the own device does not apply ULCoM, transmission power setting section 1089 sets transmission power based on the above equation (1) using propagation loss PL ₁ with the base station device of the connected cell (ST43).

FIG. 20 is a flowchart showing the procedure of the aspect 3 of the transmission power control method according to the invention.
It is determined whether the mobile terminal is a mobile terminal to which ULCoMP is applied (ST51). If the mobile terminal is a mobile terminal to which ULCoMP is applied, the base station apparatus calculates a combined propagation loss PL _CoMP by the PL _CoMP calculation unit 20892, This is applied to the closed loop transmission power control of the mobile terminal (ST52). Then, the TPC command processing unit 20893 generates a TPC command from the difference between the measured reception level and the target reception level. The transmission power control unit 2089 executes closed loop transmission power control and transmits a TPC command to the mobile terminal (ST54). On the other hand, if it is not a mobile terminal to which ULCoMP is applied, the base station apparatus applies the propagation loss PL ₁ to the closed-loop transmission power control of the mobile terminal (ST53). Then, the TPC command processing unit 20893 generates a TPC command from the difference between the measured reception level and the target reception level. The transmission power control unit 2089 executes closed loop transmission power control and transmits a TPC command to the mobile terminal (ST54).

FIG. 21 is a flowchart showing the procedure of the aspect 4 of the transmission power control method according to the invention.
In the mobile terminal, it is determined whether or not the device itself is ULCoMP-applied and recognized (ST61), and if the device recognizes that the device is ULCoMP-applied, the transmission power setting unit of the mobile terminal 1089 calculates the combined transmission power P _CoMP as transmission power (ST62). On the other hand, if the own apparatus does not apply ULCoM, transmission power setting section 1089 calculates transmission power P ₁ by the normal method using the above equation (1) and sets it as transmission power (ST63).

FIG. 22 is a flowchart showing the procedure of the aspect 5 of the transmission power control method according to the invention.
It is determined whether or not the mobile terminal is a mobile terminal to which ULCoMP is applied (ST71). If the mobile terminal is a mobile terminal to which ULCoMP is applied, the TPC command processing unit 20893 of the base station apparatus generates a TPC command for ULCoMP. The TPC command is notified to the mobile terminal by UL grant (ST72). On the other hand, if it is not a mobile terminal to which ULCoMP is applied, TPC command processing section 20893 of the base station apparatus generates a normal TPC command and notifies this TPC command to the mobile terminal with UL grant (ST73).

FIG. 23 is a flowchart showing the procedure of the aspect 6 of the transmission power control method according to the invention.
It is determined whether the mobile terminal is a mobile terminal to which ULCoMP is applied (ST81). If the mobile terminal is a mobile terminal to which ULCoMP is applied, the content of the ULOI is changed by the OI processing unit 2086 of the base station apparatus of the ULCoMP cooperating cell ( It is determined whether or not the ULOI restriction is canceled (ST82). When changing the contents of the ULOI, the base station apparatus of the ULCoMP cooperating cell immediately updates the ULOI and notifies the base station apparatus of the connected cell (ST83). On the other hand, when the content of ULOI is not changed, it is determined whether or not the content of ULHII is changed (to cancel ULHII restriction) by HII processing unit 2087 of the base station apparatus of the connected cell (ST84). When changing the contents of ULHII, the base station apparatus of the connected cell immediately updates ULHII and notifies the base station apparatus of the connected cell (ST85).

FIG. 24 is a flowchart showing the procedure of the aspect 7 of the transmission power control method according to the invention.
It is determined whether or not the mobile terminal is a mobile terminal to which ULCoMP is applied (ST91). If the mobile terminal is a mobile terminal to which ULCoMP is applied, the OLI processing unit 2088 of the base station apparatus of the ULCoMP cooperating cell transmits to the mobile terminal (past Whether or not OI is notified is determined (ST92). If the OI has been notified to the mobile terminal (in the past), the OLI processing unit 2088 of the base station apparatus of the ULCoMP cooperating cell immediately notifies the mobile terminal to reset the content of the OI (ST93).

In addition, the embodiment disclosed this time is an example in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

The present invention is useful for an LTE-A system radio base station apparatus, mobile terminal apparatus, and transmission power control method.

This application is based on Japanese Patent Application No. 2009-148998 filed on June 23, 2009. All this content is included here.

Claims

A first propagation loss PL 1 between the mobile terminal device and the first radio base station device to which the mobile terminal device is connected; and a second propagation loss that is the smallest for the mobile terminal device and the mobile terminal device. When the difference (PL 2 -PL 1 ) between the second propagation loss PL 2 with the radio base station device is within a predetermined range, uplink multipoint reception is performed for the mobile terminal device Multipoint reception processing means to be applied, and transmission power control when uplink multipoint reception is applied when the uplink multipoint reception is applied, and uplink multipoint reception when the uplink multipoint reception is not applied And a transmission power control means for performing transmission power control when not applied.
The radio base station apparatus performs fractional transmission power control by the radio base station apparatus, and the transmission power control means includes an attenuation coefficient when uplink multipoint reception is applied and an attenuation coefficient when uplink multipoint reception is not applied. The radio base station apparatus according to claim 1, wherein:
The radio base station apparatus is a radio base station apparatus that performs fractional transmission power control, wherein the transmission power control means uses the first transmission loss difference instead of the first propagation loss difference as a propagation loss when uplink multipoint reception is applied. 2. A propagation loss difference obtained by using a propagation loss obtained from one propagation loss and a propagation loss between the second radio base station apparatus and the mobile terminal apparatus is used. Wireless base station equipment.
The radio base according to claim 1, wherein the transmission power control means makes a transmission power control amount when uplink multipoint reception is applied larger than a transmission power control amount when uplink multipoint reception is not applied. Station equipment.
When the radio base station apparatus performs control using UL Overload Indication and the number of mobile terminal apparatuses to which the uplink multipoint reception is applied has changed, the contents of UL Overload Indication The radio base station apparatus according to claim 1, further comprising an OI processing unit for changing the frequency.
When the radio base station apparatus performs control using UL High Interference Indication and the number of mobile terminal apparatuses to which the uplink multipoint reception is applied is changed, UL High Interference Indication 2. The radio base station apparatus according to claim 1, further comprising HII processing means for changing the contents of the radio base station.
The radio base station apparatus is a radio base station apparatus that performs control using an Overload Indicator, and notifies the mobile terminal apparatus that applies the uplink multipoint reception that the contents of the Overload Indicator are to be reset. The radio base station apparatus according to claim 1, wherein:
The radio base station apparatus according to claim 1, wherein a notification signal for applying / not applying uplink multipoint reception is transmitted to a mobile terminal apparatus to which uplink multipoint reception is applied.
Uplink multipoint reception notification signal processing means for receiving uplink multipoint reception applied / non-applied notification signals transmitted from the radio base station apparatus and transmission power control parameters transmitted from the radio base station apparatus are received. A transmission power control parameter receiving means for transmitting and setting transmission power using a transmission power control parameter different from the transmission power control parameter when the uplink multipoint reception is not applied when the uplink multipoint reception is applied A mobile terminal apparatus comprising: a power setting unit;
The transmission power setting means sets transmission power using an attenuation coefficient when uplink multipoint reception is applied when the uplink multipoint reception is applied, and uplink multipoint when the uplink multipoint reception is not applied. The mobile terminal apparatus according to claim 9, wherein transmission power is set using an attenuation coefficient when reception is not applied.
The transmission power setting means uses the first propagation loss as the propagation loss when uplink multipoint reception is applied, instead of the first propagation loss with the connected radio base station apparatus, and the mobile terminal apparatus. The mobile terminal apparatus according to claim 9, wherein a propagation loss obtained by using a propagation loss between a base station apparatus and a radio base station apparatus to which the uplink multipoint reception is applied is used.
The transmission power setting means includes a transmission power obtained from a first propagation loss with a connected first radio base station apparatus and a propagation loss between a radio base station apparatus to which uplink multipoint reception is applied. 10. The mobile terminal apparatus according to claim 9, wherein the transmission power is set using the transmission power obtained from the following.
The transmission power setting means sets transmission power with a transmission power control amount larger than a transmission power control amount when the uplink multipoint reception is not applied when the uplink multipoint reception is applied. The mobile terminal device according to claim 9.
The mobile terminal apparatus according to claim 9, wherein the mobile terminal apparatus receives a notification signal applied / non-applied to uplink multipoint reception, transmitted from a base station apparatus of a cooperative cell for uplink multipoint reception.
In the first radio base station apparatus to which the mobile terminal apparatus is connected, the first propagation loss PL 1 between the mobile terminal apparatus and the second with the smallest propagation loss with respect to the mobile terminal apparatus and the mobile terminal apparatus When the difference (PL 2 -PL 1 ) between the second propagation loss PL 2 with the radio base station device is within a predetermined range, uplink multipoint reception is performed for the mobile terminal device And applying a transmission power control parameter when applying uplink multipoint reception to the mobile terminal apparatus when applying the uplink multipoint reception, and transmitting the uplink power when the uplink multipoint reception is not applied. Transmitting a transmission power control parameter when multipoint reception is not applied to the mobile terminal device;
In the mobile terminal apparatus, a step of receiving a transmission power control parameter transmitted from the first radio base station apparatus, and transmission when the uplink multipoint reception is not applied when the uplink multipoint reception is applied And a step of setting the transmission power using a transmission power control parameter different from the power control parameter.
The said 1st radio base station apparatus has the process of notifying application / non-application of uplink multipoint reception with respect to the mobile terminal apparatus which applies uplink multipoint reception, The step of Claim 15 characterized by the above-mentioned. Transmission power control method.